Seroprevalence of anti-SARS-CoV-2 IgG antibodies in Geneva, Switzerland (SEROCoV-POP): a population-based study.

Assessing the burden of COVID-19 on the basis of medically attended case numbers is suboptimal given its reliance on testing strategy, changing case definitions, and disease presentation. Population-based serosurveys measuring anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) antibodies provide one method for estimating infection rates and monitoring the progression of the epidemic. Here, we estimate weekly seroprevalence of anti-SARS-CoV-2 antibodies in the population of Geneva, Switzerland, during the epidemic. The SEROCoV-POP study is a population-based study of former participants of the Bus Santé study and their household members. We planned a series of 12 consecutive weekly serosurveys among randomly selected participants from a previous population-representative survey, and their household members aged 5 years and older. We tested each participant for anti-SARS-CoV-2-IgG antibodies using a commercially available ELISA. We estimated seroprevalence using a Bayesian logistic regression model taking into account test performance and adjusting for the age and sex of Geneva's population. Here we present results from the first 5 weeks of the study. Between April 6 and May 9, 2020, we enrolled 2766 participants from 1339 households, with a demographic distribution similar to that of the canton of Geneva. In the first week, we estimated a seroprevalence of 4·8% (95% CI 2·4-8·0, n=341). The estimate increased to 8·5% (5·9-11·4, n=469) in the second week, to 10·9% (7·9-14·4, n=577) in the third week, 6·6% (4·3-9·4, n=604) in the fourth week, and 10·8% (8·2-13·9, n=775) in the fifth week. Individuals aged 5-9 years (relative risk [RR] 0·32 [95% CI 0·11-0·63]) and those older than 65 years (RR 0·50 [0·28-0·78]) had a significantly lower risk of being seropositive than those aged 20-49 years. After accounting for the time to seroconversion, we estimated that for every reported confirmed case, there were 11·6 infections in the community. These results suggest that most of the population of Geneva remained uninfected during this wave of the pandemic, despite the high prevalence of COVID-19 in the region (5000 reported clinical cases over <2·5 months in the population of half a million people). Assuming that the presence of IgG antibodies is associated with immunity, these results highlight that the epidemic is far from coming to an end by means of fewer susceptible people in the population. Further, a significantly lower seroprevalence was observed for children aged 5-9 years and adults older than 65 years, compared with those aged 10-64 years. These results will inform countries considering the easing of restrictions aimed at curbing transmission. Swiss Federal Office of Public Health, Swiss School of Public Health (Corona Immunitas research program), Fondation de Bienfaisance du Groupe Pictet, Fondation Ancrage, Fondation Privée des Hôpitaux Universitaires de Genève, and Center for Emerging Viral Diseases.

Stringhini S ，Wisniak A ，Piumatti G ，Azman AS ，Lauer SA ，Baysson H ，De Ridder D ，Petrovic D ，Schrempft S ，Marcus K ，Yerly S ，Arm Vernez I ，Keiser O ，Hurst S ，Posfay-Barbe KM ，Trono D ，Pittet D ，Gétaz L ，Chappuis F ，Eckerle I ，Vuilleumier N ，Meyer B ，Flahault A ，Kaiser L ，Guessous I ... -  《-》

Prevalence of SARS-CoV-2 infection in India: Findings from the national serosurvey, May-June 2020.

Murhekar MV ，Bhatnagar T ，Selvaraju S ，Rade K ，Saravanakumar V ，Vivian Thangaraj JW ，Kumar MS ，Shah N ，Sabarinathan R ，Turuk A ，Anand PK ，Asthana S ，Balachandar R ，Bangar SD ，Bansal AK ，Bhat J ，Chakraborty D ，Rangaraju C ，Chopra V ，Das D ，Deb AK ，Devi KR ，Dwivedi GR ，Salim Khan SM ，Haq I ，Kumar MS ，Laxmaiah A ，Madhuka ，Mahapatra A ，Mitra A ，Nirmala AR ，Pagdhune A ，Qurieshi MA ，Ramarao T ，Sahay S ，Sharma YK ，Shrinivasa MB ，Shukla VK ，Singh PK ，Viramgami A ，Wilson VC ，Yadav R ，Girish Kumar CP ，Luke HE ，Ranganathan UD ，Babu S ，Sekar K ，Yadav PD ，Sapkal GN ，Das A ，Das P ，Dutta S ，Hemalatha R ，Kumar A ，Narain K ，Narasimhaiah S ，Panda S ，Pati S ，Patil S ，Sarkar K ，Singh S ，Kant R ，Tripathy S ，Toteja GS ，Babu GR ，Kant S ，Muliyil JP ，Pandey RM ，Sarkar S ，Singh SK ，Zodpey S ，Gangakhedkar RR ，S Reddy DC ，Bhargava B ... -  《-》

Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study.

Spain is one of the European countries most affected by the COVID-19 pandemic. Serological surveys are a valuable tool to assess the extent of the epidemic, given the existence of asymptomatic cases and little access to diagnostic tests. This nationwide population-based study aims to estimate the seroprevalence of SARS-CoV-2 infection in Spain at national and regional level. 35 883 households were selected from municipal rolls using two-stage random sampling stratified by province and municipality size, with all residents invited to participate. From April 27 to May 11, 2020, 61 075 participants (75·1% of all contacted individuals within selected households) answered a questionnaire on history of symptoms compatible with COVID-19 and risk factors, received a point-of-care antibody test, and, if agreed, donated a blood sample for additional testing with a chemiluminescent microparticle immunoassay. Prevalences of IgG antibodies were adjusted using sampling weights and post-stratification to allow for differences in non-response rates based on age group, sex, and census-tract income. Using results for both tests, we calculated a seroprevalence range maximising either specificity (positive for both tests) or sensitivity (positive for either test). Seroprevalence was 5·0% (95% CI 4·7-5·4) by the point-of-care test and 4·6% (4·3-5·0) by immunoassay, with a specificity-sensitivity range of 3·7% (3·3-4·0; both tests positive) to 6·2% (5·8-6·6; either test positive), with no differences by sex and lower seroprevalence in children younger than 10 years (<3·1% by the point-of-care test). There was substantial geographical variability, with higher prevalence around Madrid (>10%) and lower in coastal areas (<3%). Seroprevalence among 195 participants with positive PCR more than 14 days before the study visit ranged from 87·6% (81·1-92·1; both tests positive) to 91·8% (86·3-95·3; either test positive). In 7273 individuals with anosmia or at least three symptoms, seroprevalence ranged from 15·3% (13·8-16·8) to 19·3% (17·7-21·0). Around a third of seropositive participants were asymptomatic, ranging from 21·9% (19·1-24·9) to 35·8% (33·1-38·5). Only 19·5% (16·3-23·2) of symptomatic participants who were seropositive by both the point-of-care test and immunoassay reported a previous PCR test. The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas. Most PCR-confirmed cases have detectable antibodies, but a substantial proportion of people with symptoms compatible with COVID-19 did not have a PCR test and at least a third of infections determined by serology were asymptomatic. These results emphasise the need for maintaining public health measures to avoid a new epidemic wave. Spanish Ministry of Health, Institute of Health Carlos III, and Spanish National Health System.

Pollán M ，Pérez-Gómez B ，Pastor-Barriuso R ，Oteo J ，Hernán MA ，Pérez-Olmeda M ，Sanmartín JL ，Fernández-García A ，Cruz I ，Fernández de Larrea N ，Molina M ，Rodríguez-Cabrera F ，Martín M ，Merino-Amador P ，León Paniagua J ，Muñoz-Montalvo JF ，Blanco F ，Yotti R ，ENE-COVID Study Group ... -  《-》

SARS-CoV-2 antibody prevalence in Brazil: results from two successive nationwide serological household surveys.

Population-based data on COVID-19 are essential for guiding policies. There are few such studies, particularly from low or middle-income countries. Brazil is currently a hotspot for COVID-19 globally. We aimed to investigate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody prevalence by city and according to sex, age, ethnicity group, and socioeconomic status, and compare seroprevalence estimates with official statistics on deaths and cases. In this repeated cross-sectional study, we did two seroprevalence surveys in 133 sentinel cities in all Brazilian states. We randomly selected households and randomly selected one individual from all household members. We excluded children younger than 1 year. Presence of antibodies against SARS-CoV-2 was assessed using a lateral flow point-of-care test, the WONDFO SARS-CoV-2 Antibody Test (Wondfo Biotech, Guangzhou, China), using two drops of blood from finger prick samples. This lateral-flow assay detects IgG and IgM isotypes that are specific to the SARS-CoV-2 receptor binding domain of the spike protein. Participants also answered short questionnaires on sociodemographic information (sex, age, education, ethnicity, household size, and household assets) and compliance with physical distancing measures. We included 25 025 participants in the first survey (May 14-21) and 31 165 in the second (June 4-7). For the 83 (62%) cities with sample sizes of more than 200 participants in both surveys, the pooled seroprevalence increased from 1·9% (95% CI 1·7-2·1) to 3·1% (2·8-3·4). City-level prevalence ranged from 0% to 25·4% in both surveys. 11 (69%) of 16 cities with prevalence above 2·0% in the first survey were located in a stretch along a 2000 km of the Amazon river in the northern region. In the second survey, we found 34 cities with prevalence above 2·0%, which included the same 11 Amazon cities plus 14 from the northeast region, where prevalence was increasing rapidly. Prevalence levels were lower in the south and centre-west, and intermediate in the southeast, where the highest level was found in Rio de Janeiro (7·5% [4·2-12·2]). In the second survey, prevalence was similar in men and women, but an increased prevalence was observed in participants aged 20-59 years and those living in crowded conditions (4·4% [3·5-5·6] for those living with households with six or more people). Prevalence among Indigenous people was 6·4% (4·1-9·4) compared with 1·4% (1·2-1·7) among White people. Prevalence in the poorest socioeconomic quintile was 3·7% (3·2-4·3) compared with 1·7% (1·4-2·2) in the wealthiest quintile. Antibody prevalence was highly heterogeneous by country region, with rapid initial escalation in Brazil's north and northeast. Prevalence is strongly associated with Indigenous ancestry and low socioeconomic status. These population subgroups are unlikely to be protected if the policy response to the pandemic by the national government continues to downplay scientific evidence. Brazilian Ministry of Health, Instituto Serrapilheira, Brazilian Collective Health Association, and the JBS Fazer o Bem Faz Bem.

Hallal PC ，Hartwig FP ，Horta BL ，Silveira MF ，Struchiner CJ ，Vidaletti LP ，Neumann NA ，Pellanda LC ，Dellagostin OA ，Burattini MN ，Victora GD ，Menezes AMB ，Barros FC ，Barros AJD ，Victora CG ... -  《Lancet Global Health》

High seroprevalence for SARS-CoV-2 among household members of essential workers detected using a dried blood spot assay.

McDade TW ，McNally EM ，Zelikovich AS ，D'Aquila R ，Mustanski B ，Miller A ，Vaught LA ，Reiser NL ，Bogdanovic E ，Fallon KS ，Demonbreun AR ... -  《PLoS One》